This application is based on patent application No. 10-121831 filed Apr. 15, 1998 in Japan, the content of which is incorporated hereinto by reference.
1. Field of the Invention
The present invention relates to a printing apparatus for printing information, such as a document and an image processed by an information processing system, on a printing medium, such as a paper, and a feeding control method of the printing medium.
2. Description of the Related Art
Demand in the market for down-sizing and weight saving for a printer as a printing apparatus has been growing similarly to other various devices. For satisfying such demand, down-sizing and weight saving in the printer has been progressed significantly. Seeking for down-sizing of the printer, there has been proposed a printer, in which a main body portion of the printer performing image printing and an automatic sheet feeder (hereinafter referred to as xe2x80x9cASFxe2x80x9d) portion for feeding a plurality of stacked sheets as printing medium to an image forming portion one by one are separated, and the ASF portion is thus made independent of the main body of the printer for external attachment, as disclosed in Japanese Patent Application Laid-open No. 4-303336 (1992). On the other hand, not only in the small size printer, but also in a printer having a plurality of paper feeding opening or a printer permitting only manual paper feeding, there has been conventionally known to ASFs"" which can be externally installed. It should be noted that various media in addition to paper is included as the printing medium.
In such printers, on which an external ASF is installed, most of the printers permits manual feeding of the printing media while the external ASF is not installed. However, in such manual feeding, since the sheet cannot be supplied stably as in the ASF, the sheet may be obliquely pressed onto a nip portion formed by a transporting roller and a pinch roller to cause skewing of the sheet, or depression force for the sheet pressed to the nip portion may lack or excessively small to possibly cause lack of margin (lead) amount of the tip end of the sheet.
In order to take a measure for the problems set forth above, there is a printer which is provided with a discharged paper sensor at a position on a downstream side in a sheet transporting direction of a printing head, for example. In case of such printer, upon performing printing operation, at first, a tip end of the sheet has to be drawn to a position on the downstream side in the sheet transporting direction across a print start position by the printing head. Then, when the discharged paper sensor detects the sheet, judgment is made that paper feeding is successful, and the tip end of the sheet is backed to the print start position. On the other hand, when the discharged paper sensor does not detect the sheet, judgment is made that paper feeding is failed, and the sheet is discharged. Thus, upon manual paper feeding, skewing of the sheet or lacking of the tip end margin can be successfully avoided.
However, the conventional printer set forth above encounters the following problem.
Namely, in the printer having the discharged paper sensor, as set forth above, even upon automatic paper feeding while the external ASF is installed, the following problem is encountered if a control depending upon whether the sheet is detected by the discharged paper sensor or not is performed. When operation to return the tip end of the sheet back to the print start position is performed upon detection of the sheet by the discharged paper sensor, extra period is required for returning the tip end of the sheet back to the print start position, and throughput is lowered. Furthermore, upon returning the sheet in backward direction in the transporting direction, a rear end of the sheet abuts onto a mechanical part within the ASF to cause holding of the sheet or mis-feeding.
It is therefore an object of the present invention to provide a printing apparatus and a feeding control method which realizes highly reliable feeding upon feeding of a printing medium, such as paper or the like by manual feeding, prevents lowering of throughput in automatic paper feeding of an automatic paper feeding apparatus, and realizes highly reliable feeding by preventing holding of the printing medium or mis-feeding.
In the first aspect of the present invention, there is provided a printing apparatus for printing an image using a printing head on a printing medium fed automatically and a printing medium fed manually, comprising:
a transporting roller for transporting the printing medium, the printing head and a sensor for detecting the printing medium arranged sequentially in a direction from an upstream side to a downstream side in a transporting direction of the printing medium, and
control means for transporting the printing medium by a transporting roller in amount sufficient for reaching a tip end of the printing medium to a detecting position of the sensor when the printing medium is fed manually, to execute feeding confirmation process for judgment whether the sensor detects the printing medium or not and whereby whether feeding is successful or not, and not executing the feeding confirmation process when the printing medium is fed automatically.
In the second aspect of the present invention, there is provided a printing apparatus installable to an automatic feeding apparatus feeding a printing medium, printing an image using a printing head on a printing medium fed from the automatic feeding apparatus when the printing apparatus is installed to the automatic feeding apparatus, and printing an image using the printing head on a printing medium fed manually when the printing apparatus is not installed to the automatic feeding apparatus, comprising
a transporting roller for transporting the printing medium, the printing head and a sensor for detecting the printing medium arranged sequentially in a direction from an upstream side to a downstream side in a transporting direction of the printing medium, and
control means for transporting the printing medium by a transporting roller in amount sufficient for reaching a tip end of the printing medium to a detecting position of the sensor when the printing medium is fed manually, to execute feeding confirmation process for judgment whether the sensor detects the printing medium or not and whereby whether feeding is successful or not, and not executing the feeding confirmation process when the printing medium is fed by the automatic feeding apparatus.
In the third aspect of the present invention, there is provided a feeding control method of a printing apparatus in which a transporting roller for transporting a printing medium, a printing head and a sensor for detecting the printing medium are sequentially arranged from upstream side to downstream side in a transporting direction of the printing medium and printing an image on the fed printing, comprising:
step of feeding the printing medium by automatic feeding and manual feeding; and
step of transporting the printing medium by a transporting roller in amount sufficient for reaching a tip end of the printing medium to a detecting position of the sensor when the printing medium is fed manually, to execute feeding confirmation process for judgment whether the sensor detects the printing medium or not and whereby whether feeding is successful or not, and not executing the feeding confirmation process when the printing medium is fed automatically.
According to the present invention, in case of automatic feeding of a printing medium, an operation for once feeding the printing medium up to a position of a sensor on downstream side in the printing medium transporting direction of a printing head, is not required. Therefore, in case of automatic feeding employing an automatic feeding apparatus, it becomes unnecessary to return the printing medium from the position opposing to the sensor to a print start position. Accordingly, a rear end of the printing medium will never abut to an internal component of the automatic feeding apparatus. Thus, unwanted holding of the printing medium or mis-feeding of the printing medium can be successfully prevented. On the other hand, since it is not required to return the printing medium in backward direction in the transporting direction, it contributes in improvement of throughput. Of course, if automatic feeding is performed employing the automatic feeding apparatus, since much stable sheet feeding operation can be performed in comparison with manual feeding, skewing of the printing medium or lacking of tip end margin on the printing medium can be successfully prevented even without checking by once feeding the printing medium up to the position of the sensor.
Furthermore, in manual feeding, by making judgment whether feeding is successful or not utilizing the sensor in the similar manner as that in the prior art, skewing of the printing medium, lacking of tip end margin and so on can be eliminated.
As a result set forth above, it becomes possible to provide highly reliable printing apparatus and feeding control method.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of the embodiments thereof taken in conjunction with the accompanying drawings.